| ventilators, negative-pressure | Body ventilators that assist ventilation by applying intermittent subatmospheric pressure around the thorax, abdomen, or airway and periodically expand the chest wall and inflate the lungs. They are relatively simple to operate and do not require tracheostomy. These devices include the tank ventilators ("iron lung"), portalung, pneumowrap, and chest cuirass ("tortoise shell"). (12 Dec 1998) |
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| ventricular filling pressure | The pressure in the ventricle as it fills with blood, ordinarily equivalent to the mean atrial pressure when there is no A-V valvular gradient. Atrial pressure can be used in place of transmural pressure because pericardial pressure usually varies between -2 and +2 mm Hg and hence is negligible. During cardiac tamponade, pericardial and atrial pressures equilibrate so that transmural pressure is zero and the high atrial presures cannot be "filling" pressures. (05 Mar 2000) |
| ventricular pressure | The pressure within a cardiac ventricle. Ventricular pressure waveforms can be measured in the beating heart by catheterization or estimated using imaging techniques (e.g., doppler echocardiography). The information is useful in evaluating the function of the myocardium, cardiac valves, and pericardium, particularly with simultaneous measurement of other (e.g., aortic or atrial) pressures. (12 Dec 1998) |
| partial pressure | The pressure exerted by a single component of a mixture of gases, commonly expressed in mm Hg or torr; for a gas dissolved in a liquid, the partial pressure is that of a gas that would be in equilibrium with the dissolved gas. Formerly, symbolised by p, followed by the chemical symbol in capital letters (e.g., pCO2, pO2); now, in respiratory physiology, P, followed by subscripts denoting location and/or chemical species (e.g., PCO2, PO2, PaCO2). (05 Mar 2000) |
| mean arterial pressure | <cardiology, physiology> The average value for arterial pressure. Systolic pressure + diastolic pressure divided by 2. (27 Sep 1997) |
| central venous pressure | The venous pressure as measured at the right atrium, done by means of a catheter introduced through the median cubital vein to the superior vena cava, the distal end of the catheter being attached to a manometer. (12 Dec 1998) |
| cerebrospinal fluid pressure | Manometric pressure of the cerebrospinal fluid as measured by lumbar, cerebroventricular, or cisternal puncture. Within the cranial cavity it is called intracranial pressure. (12 Dec 1998) |
| cerebrospinal pressure | The pressure of the cerebrospinal fluid, normally 100 to 150 mm of water, relative to the ambient atmospheric pressure. (05 Mar 2000) |
| chromatography, high pressure liquid | Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. (12 Dec 1998) |
| root pressure | <botany> Pressure in the roots which, when the shoot is cut off, will cause liquid to ooze from the root stump, the mechanisms and tissues involved in this process are not clearly understood. (09 Oct 1997) |
| phrenic pressure test | Pressure is made on the phrenic nerve on each side, above the clavicles where the nerve passes over the scalenus anticus muscle; if pain is felt and the patient inclines his head to the painful side, the problem is in the pleural space; if his head does not incline to one side, the problem is in the abdominal cavity. (05 Mar 2000) |
| wedge pressure | The intravascular pressure reading obtained when a fine catheter is advanced until it completely occludes a small blood vessel or is sealed in place by inflation of a small cuff; commonly measured in the lung to estimate left atrial pressure. (05 Mar 2000) |
| pleural pressure | The pressure in the pleural space between the visceral and parietal pleurae. (05 Mar 2000) |
| continuous positive airway pressure | A technique of respiratory therapy, in either spontaneously breathing or mechanically ventilated patients, in which airway pressure is maintained above atmospheric pressure throughout the respiratory cycle by pressurization of the ventilatory circuit. (05 Mar 2000) |
| continuous positive pressure breathing | Artificial ventilation in which all inspirations are provided by positive pressure applied to the airway. Synonym: continuous positive pressure breathing, continuous positive pressure ventilation, intermittent positive pressure breathing, intermittent positive pressure ventilation. (05 Mar 2000) |